Process of preparing secondary and tertiary aliphatic amines from primary aliphatic bases



Patented May 10, 1932 OTTO NICODEMUS AND WALTER soHMIn'r, or; renewomemmamm-aocesw;

GERMANY, ASSIGNORS TO I. G. FABBENINDUSTBIE axrrmveesntnscnarn: or.

FBANKFORT-ON-THE-MAIN, GERMANY, A conrona'rroiv onennrranr W I rnoonss or PREPARING snconnnmr AND TERTIARY Amefia'ric'iinmnsritoilt PRIMARY anrrna'rro BASES v v No Drawing. Application filed November 18, 1929, Serial No. 408,154, and ii Germany Noven'mer 27,1928. I

The present invention relates to process of preparing secondary and tertiary aliphatic amines from primary aliphatic bases.

The manufacture of secondary aliphatic bases from primary amines by catalytic elimination of ammonia in the gaseous phase has already often been the subject of investigations. These trials have, however, not led to the desired result because the elimination of ammonia was always accompanied by a dehydrogenation of the aliphatic bases and with a decomposition of the products of dehydrogenation.

We have now found that primary aliphatic amines in the gaseous phase can be converted catalytically in an easy manner, with elimination of ammonia, into secondary and tertiary bases without accompanying decomposition into hydrocarbons or dehydrogenation to nitriles, if case is taken that the working temperatures are below 300 C. As suitable catalysts for this purpose are the metals which are known to have hydrogenating 0r clehydrogenating action, stance, copper, cobalt, nickel or platinum. According to the character of the metal used the temperature at which the desired change occurs and the yield of converted primary bases vary; in most cases the temperature is about 200 C. when copper is used, it is somewhat higher, about 260 C.280 C. Only above the optimum working temperatures do the metals determine dehydrogenation and decomposition.

The preferred mode of operating consists in passing the aliphatic primary base, such as for instance methylamine, ethylamine or butylamine, in gaseous state over a metal which is known to be a hydrogenating catalyst, the metal being in a finely subdivided form, advantageously carried on a porous material and heated, according to the character of the metal, to a temperature of between 150 C. and 280 C. From the product secondary and tertiary aliphatic amines are obtained besides ammonia;-whether the secondary amines or the tertiary amines are produced in the larger or predominating proportion depends mainly on gaseous current.

such as, for in.

the velocity of the The. following examples serve to illustrate our invention, but they are'notlintendedto' limit it theretoz y i 1::fA*continuous' curr nt of ethylamine is passed at a temperature between 260 C. and 270 (1, over a contact containing about. 6 per centot' copper whichis prepared by sub- ]ecting copper carbonate carried on pumice stone to careful reduction in a current of hydrogen. The velocity of the vapor of ethylamine is regulated in such a manner that every hour 140-150 grams of the amine pass the tube filled with two liters of a catalyst of copper. The products leaving the contact are cooled in stages, the first refrigerator being kept at a temperature between 30 C. and 40 C. and thelast at -10 C. In the first refrigerator ethylamine formed are condensed, whilst the unchanged ethylamine is liquefied in the lowtemperature refrigeratorand thereby separated from the ammonia which has been formed. The unchanged .ethylamine, which amounts to about 2530 per cent. of the ethylamine used during one passage over the contact, is reconducted into the contact chamber.

The crude product condensed at the higher temperature consists of, -per cent. of diethylamine and 28 per cent. of triethylamine, the rest being condensation prod ucts of higher boiling point;

2. Vapor of eth lamine is'passed at a temperature between 220 C. and 280 C. over a contact made by subjecting cobalt carbonate carried on pumice stone to reduction by a current of hydrogen, the velocity being such that 65 per cent. of the vapor is converted. By working up the product as described above, a condensate is obtained which contains 78 per cent. of diethylamine and 20 per cent. of tri-ethylamlne- By fractionating the condensate strength can easily be obtained.

3. Vapor of normal butylamine is passed over the contact described in Example 1 so that about 70 per cent. of the butylamine is converted. The condensate obtained as described in Example 1 consists of 7 6 per cent. of dibutylamine,the rest being tributylamine diethylamine of per cent. 0

and small quantities of condensation products.

We claim: c 1. Process of preparing secondary and tertiary aliphatic amines from primary aliphatic amines, which comprises passing the vapor ofa primary aliphatic amine at a temperai ture' below 300 C. over a metal which is known to be a hydrogenating catalyst.

2. Process of preparing cliethylamine and triethylamine from ethylamine, which com- 7 prises passing the Vapor ofethylamine at a temperature below 300 C. over a metal which is known to be a hydrogenating catalyst.

3. Process of preparing diethylamine and triethylamine from ethylamine, which comprises passing the vapor of ethylamine at 260 C. to 280 C. over a catalyst of copper. In testimony whereof, we afiix our signatures.

.7 OTTO NICODEMUS. -WALTER SCHMIDT. 

